python基础学习第三天上（学生信息管理小案例）

#Student类（属性）
class Student:
#初始化属性
      def __init__(self,sid,sname,sage,score):
            self.sid = sid
            self.sname = sname
            self.sage = sage
            self.score = score

#StudentDao类（方法）
class StudentDao:
      #定义空集合，准备装学生对象
      students =set()
      #增加学生
      def saveStudent(self,student):
             self.students.add(student)
      #删除学生
      def deleteStudent(self,sid):
            for student in self.students:
                  if student.sid==sid:
                        self.students.remove(student)
                        break
      #更新学生
      def updateStudent(self,stu):
            for student in self.students:
                  if student.sid==stu.sid:
                        students.remove(student)
                        self.students.add(stu)                       
                        break
      #根据id查询学生
      def queryStudentBySid(self,sid):
            for student in self.students:
                  if student.sid==sid:
                        return student
      #查询全部学生
      def queryAllStudent(self):
            return self.students

while True:
      print("欢 迎 使 用 中 南 大 学 学 生 管 理 系 统")
      print("1.新增学生\n2.修改学生\n3.删除学生\n4.查询所有学生\n5.按学号查询学生")
      choice=int(input("请选择..."))
      if(choice==1):
            sid=int(input("请输入添加的学生学号..."))
            sname=input("请输入添加的学生姓名...")
            sage=int(input("请输入添加的学生年龄..."))
            score=int(input("请输入添加的学生成绩..."))
            student=Student(sid,sname,sage,score)
            #调用添加方法
            studentDao = StudentDao()
            studentDao.saveStudent(student)
      elif(choice==2):
            sid=int(input("请输入要修改的学生学号..."))
            sname=input("请输入要修改的学生姓名...")
            sage=int(input("请输入要修改的学生年龄..."))
            score=int(input("请输入要修改的学生成绩..."))
            student=Student(sid,sname,sage,score)
            #调用修改方法
            studentDao=StudentDao()
            studentDao.updateStudent(student)
      elif(choice==3):
            sid=int(input("请输入要删除的学生学号..."))
            #调用删除方法
            studentDao=StudentDao()
            studentDao.deleteStudent(sid)
      elif(choice==4):
            #调用查询所有学生方法
           
            studentDao=StudentDao()
            students=studentDao.queryAllStudent()

            print("中南学生信息如下..\n")
            for student in students:
                  print("学号：%d，姓名：%s，年龄：%d，成绩：%d"%(student.sid,student.sname,student.sage,student.score))
      elif(choice==5):           
            sid=int(input("请输入要查询的学生学号..."))
            #调用查询学号的方法
            studentDao=StudentDao()
            student = studentDao.queryStudentBySid(sid)     
            print("学号：%d，姓名：%s，年龄：%d，成绩：%d"%(student.sid,student.sname,student.sage,student.score))
      elif(choice==6):
             break;

运行结果截图：